Brake



Patented Jan. 6, 1942 Gorge A.

to Bendix Aviation Corporation, Ind., a corporation of Delaware Goepfrlch, South Bend, Ind., assigner South Bend,

Application February 28,1940, serial No. 321,191 i 11 claims.' (c1. isa-19.5)

This invention relates to brakes, andis illustrated as embodied in an internal expanding automobile brake.

An object 'of the invention is to provide an adjustment which will shift the released position of the brake friction means to compensate for wear,

in combination with a brake anchorage which gradually expands the friction means in released position as its position is so shifted, in such a manner as to preserve a uniform clearance in the brake regardless of wear. Another object is to provide a simple adjustment device having a rack turning a pinion locked by means such as a spring pawl, thereby giving a, very fine adjustment.

'Ihe above and other objects of the invention, and various novel features, including the combination of a spring centralizer with the described adjustment, will be apparent from the following description of the illustrative embodiments shown in the accompanying drawings, in which: l

Figure 1 is a section th'rough a brake embodying one form of the invention, in a plane just inside the'head of the brake drum, and showing y the brake shoes in side elevation;

Figure 2 is a partial section on the line 2-2 of Figure 1;

Figure 3 is a view corresponding to the lower part of Figure 1, but showing the addition of a centering spring;

Figure 4 is a partial section corresponding to the lower part of Figure 1, but showing a modification having two pivotally-connected shoes;

Figure 5 is a partial section on the line 5 5 of Figure 4; and

Figures 6, 'l and 8 are respectively a view corresponding to Figure 3, a partial radial section through the lower part of th'e brake, and a section on the line 8-8 of Figure 6, and showing a further modification.

Figures 1 and 2 illustrate a brake having a rotat'able drum lll, at the open side of which is a support such as a backing plate l2. Within the drum is a resilient expansible friction band or shoe Il arranged to be spread to apply the .brake by suitable means such as a wheel cylinder I6 acting against the resistance oi a return spring i8. The shoe I4 is provided with suitable steady rests 2li.

The upper ends of the shoe |4 are arranged for engagement with a fixed anchor block 22 secured to the backing plate l2. The shoe ends are rounded to seat in sockets formed in the sides of the block. The lower faces of these sockets diverge somewhat, as seen at 22', so that as they ings in the shoe rim shoe ends are forced downwardly by the automatic adjustment described below'they are spread apart sufficiently to compensate for the wear causing the adjustment, thereby to preserve the clearance between the shoe and drum uniform.

I The lower portion of lthe backing plate is provided with a stop in the form of a fixed bracket 26 having a stop ange 28 curved to parallel the brake drum. The flange 28 is en$aged,-when the brake is released, by the inner end of a plunger 33, mounted for lengthwise movement'between the shoe web and a guide 32 secured to the shoe web. The plunger 33 moves radially of the shoe, and its outerf end extends through alined openand the brake lining, the extreme end being flush with the brake lining, and being arranged to engage the drum when the brake is applied. Thus th'e brake drum pushes the plunger 30 radially inward as the brake lining wears.

l One edge of the plunger 3|! is formed with rack teeth meshing with a small pinion 3l rigid with a ratchet wheel 36, the pinion and ratchet wheel unit being journaled in bearings provided by alined openings in the shoe web and the guide 32. 'I'he teeth on the ratchet wheel 38 ,are yieldingly engaged, to prevent retrograde movement, by

holding means such as a spring pawl 38 securedA to the she web. l

It will be 'seen that as the plunger 3|iis gradually pushed radially inward, pawl 33 prevents it, from jarring out again. The friction of the parts holds it sufficiently against unintended inward movement. The size of the ratchet wheel 36 gives a veryvfine adjustment. A spring-pressedplunger All` keeps the parts at all times .lightly loaded, insuring that a tooth of ratchet 36 is seated against th'e pawl 38.

As shown in Figure 3, a centering spring 42 may be looped over the flange 28, with parts gripping the plunger-30 between them and yieldingly resisting movement of the plunger in either direction. This centers the shoe when the brake is released.

In Figures 4 and 5, instead of a single resilient- 1y flexible shoe there are two pivotally connected shoes Il and 2 l. These are provided with automatically adjusted stop plungers |30 and 230, engageable with the flange |28 and 228 of bracket |26 and 226, moving in guides |32 and232, and having teeth meshing with pinions |34 and 234 rigid with ratchet wheels |36 and 236 held by spring pawls as described above.

In Figures 6, 'I and 8. the stop flange 28 is'engaged by a square-section plunger 330 formed on all -four sides with ratchet teeth engaged by with a drum, an expansible friction device, ad- Spring IJaWlS turned up from a Steel plate 336 justment means for determining the position of mounted on a bracket guide 334 secured t0 the the friction device in the drum in accordance shoe web. The four pawls on the plate 336 are with Wear, an anchorage formed to cause wearof different lengths such that any movement of o compensating expansion of lhe friction device in the plunger 330 equal t0 One-fourth of the height released position as the position of the friction of one of the teeth on its side will cause one of device is changed by the adjustment means, and

the pawls to engage its tooth. c a resilientl centralizer acting` yieldingly on said While several illustrative embodiments have means and tending to hold it on a given radius been described in detail, it is not my intention l0 0f the brake.

to limit the scope of the invention to those par- 7. A brake comprising, for use in combination ticular embodiments, 01 Otherwise than by the with a drum, an eXpanslble friction device, and

terms 0f the appended Claims. l an adjustment means for determining the posi- I claim: l tion of the friction device in the drum in ac- 1. A brake comprising, for use in combination l5 cordance with Wear, said means including a part with a drum, an expansible friction device adaptactuated by engagement with the drum and ined to anchor at either end thereof, adjustment cluding a pinion driven by a rack controlled by with the drum and means set thereby for detergrade movement of the pinion.

mining the position of the friction device in the to 8. A brake comprising, for use in combination drum in accordance with wear, and an anchorwith a drum, an expansible friction'devic'e, and age formed to cause wear-compensating expanan automatic adjustment means for determining sion of the friction device in released position as the position of the friction device in the drum the position of the friction device is changed by in accordance with wear, said means including the adjustment means. g, l agement with the drum 2. A brake comprising, for use in combination and lincludingr a pinion driven by'a vraclr conwith a drum, an expansible friction device, adtrolled by said part and a yielding pawl preventjustment means having a part actuated by ening retrograde movement. of lthe pinion. gagement with the drum and having means for 9. A brake comprising, for use in combination determining the position of the friction device in :lo with a drum, an expansible friction device, and the drum in accordance with Wear. said means a drum actuated automatic adjustment means including ar pinion driven by a rack controlled for determiningthe position of the friction dcby Said drum actua-ted part and a SOD eStab1iShvice in the drum in accordance with wear, said ing the position 0f One end 0f Said drum aCtumeans including a partactuated by engagement ated part. "i5 with the drum and includinga pinion driven by 3. A brake comprising, for use in combination a reel; controlled by Said .part and a yielding with a drum, an expansible friction device, autopawl preventing retrograde movement of the matic adjustment means having a part actuated pinion, f by engagement with the drum and means set 10. A brake comprising, Lfor use in combination thereby fOI determining the Position 0f the fIiC- 4" with a drum. an expansible friction device adapttion device in the drum in accordance with wear, ed to miler at either end thereof, automatic an anchorage fOImed U0 Cause Wear-Gempensatadjustment means for determining the position ing expansion of the friction device in released of the friction device in the drum in accordancer position as the position of the friction device is with weer, said means having a part actuated by Changed by the adjustment means, and Cell- 1'3 engagelnent Wlth the drum and having a memtraliZer acting yieldingly 0n Said mean-S. ber set by the said drum actuated part, and ,any4 4. A brake Comprising, fOr use in CombinaCiOn anchorage formed to cause Wear-compensating with a drum, an expansible friction deViCe, aUO- c expansion of the friction device in released posi-.v` matic adjustment means having a Dart aetualied tion as the position of the friction device is by engagement with the drum and means set .3u changed bythe adjustmem; megns, l thereby f01 determining the position 0f the friel1. A brake comprising. for use in combination tion device in the drum in accordance with wear, with a druma an cxpansjblc friction device adaptsaid means including a pinion driven by a rack ed to anchor at either eno thereof, automatic actuated by Said Dart, and e Centia-iZer acting adjustment means for determining the position yieldingly 0n the adjustment meanS- 75 of theffriction device in .the drum in accordance 5. A brake comprising, for use in combination with Weary Said means having a part actuated with a drum, an expansible friction device, adby engagement Wjththc drum and having' amcm justment means for determining the position of ber scc by the Said drum actuated part, and an the friction device in the drum in accordance anchorage formed no change the released pcsi with wear, and an anchorage formed as a cam` m t0 Cause Wear-compensating expansion 0f the compensate for changes in the position of the friction device in released position as the posi-` friction device caused by thc aforesaid adjusttion of the friction device is changed by the adc ment means.

justifient means. l GEORGE A. GOEPFRICH. 6. A brake comprising, for use in combination o5 

